Four Blacks, One Press: A Practical Guide to Ink Builds and Fragile Type

There is a particular email that arrives in most small-press inboxes at least once. It usually says something like: the black looks washed out on the proof, so we made it blacker. Attached is a PDF where every dark element is now a four-colour build, including the 7pt footnotes and the reverse type on the cover. The printer sighs. The schedule slips. The book gets reprinted.

Black is not a default. It is a production decision, and it behaves differently depending on where it sits: body text, a solid cover panel, a hairline rule, a logo, a barcode box. If you are sending files to a UK litho or digital printer in 2026, it is worth knowing which black you are asking for and why.

The black you see is not the black you specified

On screen, black is usually RGB 0/0/0. In print, black is ink on paper, and there are several ways to build it. The simplest is 100% K: one plate, one ink, no registration to worry about. It is the right choice for most book interiors, especially text. It is also the black that can look slightly flat on uncoated stock, which is why designers reach for a richer build.

A rich black adds cyan, magenta and yellow under the black ink. A common coated-stock build is 60C/40M/40Y/100K. A cooler version might lean on more cyan; a warmer one on a touch more magenta and yellow. These are starting points, not commandments. Your printer may have a house build, and their profile matters more than a number copied from a forum.

Then there is registration black: 100% of all four inks. That is for registration marks and trim marks, not for live type or large solids. It puts far too much ink on the sheet and can cause drying, set-off and blocking problems. If your PDF has registration black in the artwork, fix it before it reaches the press.

Interiors: small type wants a simple life

For body text, captions, footnotes and fine rules, 100% K is usually the safe call. The reason is registration. Four plates have to line up perfectly, and on a fast litho press they can drift by a fraction of a millimetre. On small type, that drift shows up as coloured fringing around the letters. On a 9pt serif, it can look like the text has been printed through a slight haze.

This matters even more with reverse type: white letters knocked out of a dark background. If the background is a four-colour build and registration wanders, the edges of the letters can pick up a cyan or magenta halo. Keep reverse type out of very fine serifs and very small sizes, and give the counters room to breathe. If you are printing on uncoated stock, dot gain will close up small gaps faster than you expect. A 6pt reverse sans might survive; a 6pt reverse Didone probably will not.

Overprint is the other trap. In many PDF workflows, 100% black text is set to overprint by default. That is often helpful: it avoids white halos where black text sits over a tint. But if you have rich black text, or black text that should knock out of a background, check the output preview. A white element set to overprint is a classic disaster. So is a dark image placed over a dark panel without trapping.

Covers: rich black earns its keep, within limits

Large solid areas are where rich black does useful work. A cover panel built from 100% K alone can look thin or grey, especially on coated stock under bookshop lighting. A controlled rich black gives depth. The limit is total area coverage, often called TAC. Coated litho jobs might run up to around 300–330%; uncoated stocks usually want less. Digital presses have their own limits and their own toner behaviour. Ask your printer for their recommended maximum and stick to it.

For covers, specify the build in your artwork notes and ask for a hard proof on the actual stock if the budget allows. A PDF proof on an office laser is not a reliable guide to a rich black. It is fine for catching typos; it is useless for judging ink density.

The test page that tells you more than a proof

A simple test page can save a lot of guessing. It does not need to be beautiful. It needs to be useful. Include patches of 100% K, your rich black build, a 100% registration patch for comparison, and a few grey tints. Add small positive type at 6pt, 7pt and 8pt in both a serif and a sans. Add reverse type at the same sizes. Add a hairline rule, a 0.25pt rule and a 0.5pt rule. Add a small overprint sample: black text over a 20% tint, and white text knocked out of a solid.

Send that page with your files, clearly labelled as a test page and not part of the final artwork. Ask the printer to run it on the intended stock and process. When it comes back, you will see how your black behaves, how much the small type fills in and whether your reverse type holds its shape. That is more useful than a hundred opinions.

A short spec sheet for your printer

Keep the notes brief and specific: the black builds you have used, your maximum TAC, whether black text is set to overprint, the smallest type size in the job, and the stock you have specified. Mention the PDF standard you have exported to, such as PDF/X-4, and the output intent. If you are using a digital printer, ask whether they prefer a different rich black build for toner. If you are using litho, ask for their house build and their tolerance for registration.

None of this is glamorous. But it is the difference between a book that looks deliberate and one that looks like it survived a fight with a press. Black is not black until you specify it. Do that, and the rest of the page has a much better chance of holding together.